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  1. #1
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    Frame materials besides steel, aluminum and carbon fiber for a recumbent build?

    I'm having a hard time finding a local supply of quality steel and aluminum tubing, and the only carbon fiber cloth supplier I can find has a few lines on their website, selling 0.5m x 100 cm x 0.35mm pieces. And they aren't replying to my messages, the quantities I need for a bicycle are probably way below their usual order quantities.

    I've considered a hollow plywood frame. I can only get 4mm, 5mm and 3/5" thicknesses locally, and only one choice in wood. I'd like to reinforce it by wrapping it in carbon fiber, but... Would fiber glass do as good a job, at a weight penalty?

    Hardwood is sort of available locally, but varies from the US varieties, and I don't have heavy duty tools to hollow it out, assuming I can glue the halves together.

    Any other thoughts?

  2. #2
    Decrepit Member Scooper's Avatar
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    It might help to know where you are.
    - Stan

  3. #3
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    A router with a plunge ball end bit and a straight edge jig, isn't what i'd consider heavy equipment, and can easily be put together for $150 with including a new router

  4. #4
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    I can't buy anything I need for my work locally. You would need to get pretty lucky to have a local supplier for bike tubes.

    I would look at the Aircraft Spruce website and order some tube and you'll be all set.


    Dave

  5. #5
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    I get most of my straight gauge tubing from Online Metals. No minimum quantity, just order what you need and it shows up in a couple of days.

    http://www.onlinemetals.com/

  6. #6
    Decrepit Member Scooper's Avatar
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    Quote Originally Posted by tshelver View Post
    Hardwood is sort of available locally, but varies from the US varieties, and I don't have heavy duty tools to hollow it out, assuming I can glue the halves together.

    Any other thoughts?
    This leads me to believe he's not in the U.S., hence my question about where he's located.
    - Stan

  7. #7
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    I've seen a few decent bamboo ones - the single main tube makes it pretty simple. There have also been a bunch made from flat aluminium plate cut to shape to make a box section. Plywood has also been done - again two sides with spacers to make a box section.
    http://www.kinetics-online.co.uk

  8. #8
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    Quote Originally Posted by tshelver View Post
    Hardwood is sort of available locally
    Yakal (Shorea laevis), Phillipine mahogany (Shorea negrosensis) and Phillipine rosewood (Petersianthus quadrialatus) all look like good candidates to me. If your local acacias like Acacia mangium are as tough as the Acacia melanoxylon that I use here in Oz, they could also be suitable.

    I started out by making a list of the woods that instruments makers use, especially those that luthiers call "tonewoods", then did some research and experimentation based on that. Some of the woods I use have a better stiffness to weight ratio than aluminium, titanium or steel. From the information I can find none of your woods is quite that high but Yakal is close.
    Last edited by Mark Kelly; 02-25-14 at 03:56 AM.

  9. #9
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    As the last poster guessed, I'm in the Philippines. Getting stuff from the USA is a rather costly and drawn out process, especially dealing with the bigger suppliers.

    Finding aluminum and so on locally (metro area of 1 million people) without going on a several hundred mile trip to Manila or Cebu is a real problem, and local welders and machinists don't have a huge amount of experience in working the stuff. I had some machine work done for other vehicles, and aluminum tubing or rod was not easily sourced. I ended up having to use brass in one application, and steel in another.

    I've found a place (Soller Composites in the USA) that seems to have no issues working with my financial and shipping constraints (Soller Composites out of NH), and can ship any carbon fiber product I may need. But I need to do a full build plan and material estimate, and having never built a composite (or any) bike before, that could take me some time and guesswork.

    The wood thing is still attractive to me, just that I've seen a lot of really ugly and heavy looking plywood (the most available material locally) bikes, especially recumbents, on the net.

    How would fiberglass work as a binding / strengthening agent in place of carbon fiber if I build a wood bike?

    My initial plan was to go with a plywood bike to work out the geometry and issues and then go for a composite as and when finances and time allow, and reuse the majority of the components.

    The plan was to build up from 5mm thick sheets, cutting out the center for all plies apart from the outer one, to lighten the build, except for where I would install the suspension, seat mount, bottom bracket and steering tube, which would be solid.
    I am guessing at 10 plies at this time.

    Last night I also looked at the hardwood option, that seems a really good option as well, IF I can find the right wood locally.

    Thanks very much for the input so far, several things I had not considered or that I need to research further were highlighted.

  10. #10
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    It wasn't a guess.

    Glass is very close in strength to carbon and a good deal tougher. It's heavier and it isn't as stiff.

    http://www.performance-composites.co...operties_2.asp
    Last edited by Mark Kelly; 02-25-14 at 05:09 AM.

  11. #11
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    You can find how-to builds for a carbon recumbent with a foam core online. Those will give you a very good idea as to how much material you need.

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  13. #13
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    Thanks Mark and others. I'll investigate the local wood suppliers and see what is available in smaller quantities (expecting some frustrations). Looks like fiberglass will be an option to strengthen joins and other parts of the build.

    The plywood option would be nice if I could find some of decent quality, as the frame laminations could be cut in as whole pieces, limiting the joining required.

  14. #14
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    Booth carbon and fiberglass work well with wood. But carbon is so stiff it mostly does not share the load, so you end up paying a lot for the carbon while being stuck with the weight of the wood. One way is to use just a little carbon on the inside, so that the bike is mostly wood, and before a load would be such as to break or deflect the wood, it goes to the carbon. But doing that requires real engineering. Carbon is a difficult material to design with. Most people don't understand it.

    Glass allows you to overlay wood and share strength and stiffness. You should mostly design for the wood to do the work, and use only glass cloth and fiber to the extent required to make the joints strong or provide waterproofness and mild knock resistance. Say 4 oz glass. As you know there are plans on the net for ply recumbent, I don't think they use fiber, but hardware for the joints, but there are lots of blogs on bonding to bamboo with everything from hemp to carbon.

    Something to read about is hardware bonding, where studs are bonded to wood. A very cheap and effective technique.

    For all this stuff epoxy resin is the go to resin, and may be a little difficult to get. There are lots of boatbuilder making wood epoxy boats in the P. though I realize it is an extensive area.

  15. #15
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    This carbon recumbent was built in the Phillipines. http://www.manytracks.com/Recumbent/Poste.HTM

  16. #16
    Senior Member PaPa's Avatar
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    Quote Originally Posted by Canaboo View Post
    This carbon recumbent was built in the Phillipines. http://www.manytracks.com/Recumbent/Poste.HTM
    Edward 'was' a BF member - banned in '09). His creaive CF trike is posted here: (post 213 in the following link) ) http://www.bikeforums.net/showthread...ictures)/page8 His email appears at the bottom of the Manytracks site Canaboo posted - would potentially prove valuable to contact him.

  17. #17
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    Quote Originally Posted by Canaboo View Post
    This carbon recumbent was built in the Phillipines. http://www.manytracks.com/Recumbent/Poste.HTM
    With the rider's legs protruding out so far in front of the axles, wouldn't that thing endo if he ever had to get on the brakes hard? Looks like the cranks would hit the ground so he wouldn't actually flip, but still.

  18. #18
    Andrew R Stewart Andrew R Stewart's Avatar
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    Quote Originally Posted by Live Wire View Post
    With the rider's legs protruding out so far in front of the axles, wouldn't that thing endo if he ever had to get on the brakes hard? Looks like the cranks would hit the ground so he wouldn't actually flip, but still.
    Sure does endo if too much ft brake is applied. Then the cranks will strike the ground. usually by this point the rider has let off the brakes only to repeat the cycle a few times until they crash into whatever they were trying to avoid or they come to an awkward stop. Things get real fun if you're cornering at the same time. The directional control that's lost with just one wheel on the ground can be hard for many riders to keep up with. Andy.

  19. #19
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    I linked to that purely to show that it was possible to get the materials in the Phillipines, not as a set example as to what should be built.

  20. #20
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    I'm now starting down the bamboo path, using epoxy and abaca (Manila hemp) as the bonding agent.

    Marine epoxy putty is commonally available, so i should be able track down what I need.

    I may use a plywood/fiberglass mix for the seat though.

    Now to source rhe rest of what I need.

    The first attempt will be a simple, unsuspended stick bike.

    I did see the local carbon fiber builds, they all seem to have imported the carbon fiber.

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